1. Field of Invention
This invention relates to micromachined or microelectromechanical system based fluid ejectors and fluid ejection methods.
2. Description of Related Art
Fluid ejectors have been developed for inkjet recording or printing. Ink jet recording apparatus offer numerous benefits, including extremely quiet operation when recording, high speed printing, a high degree of freedom in ink selection, and the ability to use low-cost plain paper. The so-called xe2x80x9cdrop-on-demandxe2x80x9d drive method, where ink is output only when required for recording, is now the conventional approach. The drop-on-demand drive method makes it unnecessary to recover ink not needed for recording.
Fluid ejectors for inkjet printing include one or more nozzles which allow the formation and control of small ink droplets to permit high resolution, resulting in the ability to print sharper characters with improved tonal resolution. In particular, drop-on-demand inkjet print heads are generally used for high resolution printers.
Drop-on-demand technology generally uses some type of pulse generator to form and eject drops. For example, in one type of print head, a chamber having an ink nozzle may be fitted with a piezoelectric wall that is deformed when a voltage is applied. As a result of the deformation, the fluid is forced out of the nozzle orifice as a drop. The drop then impinges directly on an associated printing surface. Use of such a piezoelectric device as a driver is described in JP B-1990-51734.
Another type of print head uses bubbles formed by heat pulses to force fluid out of the nozzle. The drops are separated from the ink supply when the bubbles form. Use of pressure generated by heating the ink to generate bubbles is described in JP B-1986-59911.
Yet another type of drop-on-demand print head incorporates an electrostatic actuator. This type of print head utilizes electrostatic force to eject the ink. Examples of such electrostatic print heads are disclosed in U.S. Pat. No. 4,520,375 to Kroll and Japanese Laid-Open Patent Publication No. 289351/90. The ink jet head disclosed in the 375 patent uses an electrostatic actuator comprising a diaphragm that constitutes a part of an ink ejection chamber and a base plate disposed outside of the ink ejection chamber opposite to the diaphragm. The ink jet head ejects ink droplets through a nozzle communicating with the ink ejection chamber, by applying a time varying voltage between the diaphragm and the base plate. The diaphragm and the base plate thus act as a capacitor, which causes the diaphragm to be set into mechanical motion and the fluid to exit responsive to the diaphragm""s motion. On the other hand, the ink jet head discussed in the Japan 351 distorts its diaphragm by applying a voltage to an electrostatic actuator fixed on the diaphragm. This result in suction of ink into an ink ejection chamber. Once the voltage is removed, the diaphragm is restored to its non-distorted condition, ejecting ink from the ink ejection chamber.
Fluid drop ejectors may be used not only for printing, but also for depositing photoresist and other liquids in the semiconductor and flat panel display industries, for delivering drug and biological samples, for delivering multiple chemicals for chemical reactions, for handling DNA sequences, for delivering drugs and biological materials for interaction studies and assaying, and for depositing thin and narrow layers of plastics for usable as permanent and/or removable gaskets in micro-machines.
The systems and methods of this invention provide increased electrostatic potential for fluid ejection in an electrostatic fluid ejector.
The systems and methods of this invention separately provide greater fluid ejection velocity with an electrostatic fluid ejector.
The systems and methods of this invention separately provide a bi-directional mode for fluid ejection.
The systems and methods of this invention separately provide for compensation within a sealed chamber of a non-compressible fluid.
The systems and methods of this invention separately provide an actively powered ejection cycle for ejecting fluid from a fluid ejector.
The systems and methods of this invention separately provide increased force on a fluid over the cycle of a fluid ejector.
The systems and methods of this invention separately provide higher frequency performance.
The systems and methods of this invention separately utilize a high performance dielectric.
According to various exemplary embodiments of the systems and methods of this invention, a sealed dual diaphragm is used to eject a fluid from a fluid ejector.
According to various exemplary embodiments of the systems and methods of this invention, a sealed dual diaphragm arrangement is used operate a fluid ejector in a bi-directional mode. According to other various exemplary embodiments of the systems and methods of this invention, a dual electrode arrangement is used effectuate ejecting a fluid from a fluid ejector. According to further various exemplary embodiments of the systems and methods of this invention, a dual nozzle arrangement is used to effectuate ejecting a fluid from a fluid ejector.
According to various exemplary embodiments of the systems and methods of this invention, a fluid ejector comprises a containment structure for a fluid to be ejected, a sealed dual diaphragm and a dual electrode. In various other exemplary embodiments of the systems and methods of this invention, a dielectric fluid is sealed behind a two-part diaphragm. In various other exemplary embodiments of the systems and methods of this invention, the dielectric fluid may be a high performance dielectric fluid.
These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.